The polymerization of olefins such as octadene and maleic anhydride by free radical initiation is well known in the prior art. As disclosed in U.S. Pat. No. 5,066,742, to Gupta; Vijai P., as the first step, maleic anhydride and a C.sub.2 -C.sub.8 olefin are typically polymerized in the presence of a free radical initiator in a blend of a reaction solvent selected from the group consisting of esters of acetic acid, formic acid, and propionic acid and a C.sub.6 -C.sub.12 hydrocarbon diluent. Further, imidization between a maleic anhydride and an alkyl amine group is a commonly known chemical reaction. Patent publications which have recognized these reactions include: German Patent DE 4241538, assigned to Leuna-Werke A.-G; Japanese Patent JP 94248017, assigned to Monsanto Kasel Kk.; and, Italian Patent EP 322905 A2, assigned to Montedipe S.p.A. Various other non-patent publications have also recognized these reactions. Included among them are: L. E. Colleman, Jr., J. F. Bork, and H. Donn, Jr., J. Org. Chem., 24, 185(1959); A. Matsumoto, Y. Oki, and T. Otsu, Polymer J., 23(3), 201(1991); L. Haeussler, U. Wienhold, V. Albricht, and S. Zschoche, Themochim. Acta, 277, 14(1966); W. Kim, and K. Seo, Macromol. Rapid Commun., 17, 835(1996); W. Lee, and G. Hwong, J. Appl. Polym. Sci., 59, 599(1996); 1. Vermeesch and G. Groeninckx, J. Appl. Polym. Sci., 53, 1356(1994); Y. Kita, K. Kishino, and K. Nakagawa, J. Appl. Polymer. Sci. 63, 1055 (1997).
The synthesis of various monofunctional N-alkyl and N-aryl maleimides are also well known in the prior art. These maleimides have been extensively used to improve the heat stability of homo- and especially copolymers such as ABS (poly(acrylonitrile-butadiene-styrene)) or a polyblend of poly(acrylonitrile-butadiene) and poly-(styrene-acrylonitrile); PVC (poly(vinyl chloride)); SAN (poly(styrene-co-acrylonitrile)); PMMA (poly(methyl methacrylate)); and the like. These maleimides may be copolymerized with other monomers such as acrylonitrile, butadiene, styrene, methyl methacrylate, vinyl chloride, vinyl acetate and many other comonomers. A more preferred practice in the industry is to produce copolymers of maleimides with other monomers and optionally with acrylonitrile and to blend the resultant copolymer with ABS and SAN resins. In any event, the copolymer compositions are adjusted to be fully compatible with the bulk resins (e.g., ABS and/or SAN) as shown by the presence of a single glass transition point (T.sub.g) as determined by differential scanning calorimetry (DSC). Maleimide-containing vinyl resins and their use in the manufacture of parts for automobiles, electrical and electronic machinery and appliances, because of their good heat resistance, impact resistance and moldability, are generally described, for example, in U.S Pat. No. 3,652,726, U.S. Pat. No. 3,676,404, U.S. Pat. No. 3,766,142, U.S. Pat. No. 4,039,734, U.S. Pat. No. 4,374,951, U.S. Pat. No. 4,381,373, U.S. Pat. No. 4,605,700, U.S. Pat. No. 4,683,275, U.S. Pat. No. 4,874,829, U.S. Pat. No. 4,879,343, U.S. Pat. No. 4,914,138, U.S. Pat. No. 4,954,571, U.S. Pat. No. 4,983,669, U.S. Pat. No. 5,028,651, U.S. Pat. No. 5,091,470 and U.S. Pat. No. 5,136,052. As noted above, U.S. Pat. No. 5,066,742, to Gupta; Vijai P., discloses copolymer suspensions of maleic anhydride and C.sub.2 -C.sub.8 olefins used in the manufacture of synthetic fibers. U.S. Pat. No. 5,424,380, to Doi, relates to a resin composition comprising an N-alkyl-substituted maleimide/olefin copolymer and a specified resin, which has excellent heat resistance, rigidity, izod impact strength, weather resistance and dimensional resistance. U.S. Pat. No. 4,919,925, to Ueda, et. al., disclose Diels-Alder reaction-type adduct of an alpha, beta-unsaturated dicarboxylic acid anhydride and an olefin or a derivative of the adduct as an active ingredient in deodorants. All of the above are incorporated by reference herein for all purposes as if fully set forth. It has long been recognized that two or more polymers may be blended together to form a wide variety of random or structured morphologies to obtain products that potentially offer desirable combinations of characteristics. However, it may be difficult or even impossible in practice to achieve many potential combinations through simple blending because of some inherent and fundamental problem. Frequently, the two polymers are thermodynamically immiscible, which precludes generating a truly homogeneous product. This immiscibility may not be a problem per se since often it is desirable to have a two-phase structure. However, the situation at the interface between these two phases very often does lead to problems. The typical case is one of high interfacial tension and poor adhesion between the two phases. This interfacial tension contributes, along with high viscosities, to the inherent difficulty of imparting the desired degree of dispersion to random mixtures and to their subsequent lack of stability, giving rise to gross separation or stratification during later processing or use. Poor adhesion leads, in part, to the very weak and brittle mechanical behavior often observed in dispersed blends and may render some highly structured morphologies impossible.
As a general rule, it is particularly desirable to prepare a grafted polymer having the impact strength of polypropylene and the elastomeric properties of a block copolymer and to extend the resultant copolymer with a high oil or low molecular weight component content to obtain a soft material having a low Shore A hardness. Similarly in the case of the present invention it is particularly desirable to prepare a grafted poly.alpha.-olefin-(co)-(maleimide)!, so as to obtain a soft material having a low Shore A hardness.
Thus, the oil or low molecular weight component extended grafted polymers of this invention, comprising the grafting of a poly.alpha.-olefin-(co)-(maleimide)! to a maleated polypropylene by the use of a difunctional grafting agent reactive with the anhydride groups on the centipede polymer and the maleate groups of the maleated polypropylene, are not currently known to the prior art.